drivers/watchdog/gpio_wdt.c

   1 /*
   2  * Driver for watchdog device controlled through GPIO-line
   3  *
   4  * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/err.h>
  13 #include <linux/delay.h>
  14 #include <linux/module.h>
  15 #include <linux/notifier.h>
  16 #include <linux/of_gpio.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/reboot.h>
  19 #include <linux/watchdog.h>
  20
  21 #define SOFT_TIMEOUT_MIN        1
  22 #define SOFT_TIMEOUT_DEF        60
  23 #define SOFT_TIMEOUT_MAX        0xffff
  24
  25 enum {
  26         HW_ALGO_TOGGLE,
  27         HW_ALGO_LEVEL,
  28 };
  29
  30 struct gpio_wdt_priv {
  31         int                     gpio;
  32         bool                    active_low;
  33         bool                    state;
  34         bool                    always_running;
  35         bool                    armed;
  36         unsigned int            hw_algo;
  37         unsigned int            hw_margin;
  38         unsigned long           last_jiffies;
  39         struct notifier_block   notifier;
  40         struct timer_list       timer;
  41         struct watchdog_device  wdd;
  42 };
  43
  44 static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
  45 {
  46         gpio_set_value_cansleep(priv->gpio, !priv->active_low);
  47
  48         /* Put GPIO back to tristate */
  49         if (priv->hw_algo == HW_ALGO_TOGGLE)
  50                 gpio_direction_input(priv->gpio);
  51 }
  52
  53 static void gpio_wdt_hwping(unsigned long data)
  54 {
  55         struct watchdog_device *wdd = (struct watchdog_device *)data;
  56         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
  57
  58         if (priv->armed && time_after(jiffies, priv->last_jiffies +
  59                                       msecs_to_jiffies(wdd->timeout * 1000))) {
  60                 dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
  61                 return;
  62         }
  63
  64         /* Restart timer */
  65         mod_timer(&priv->timer, jiffies + priv->hw_margin);
  66
  67         switch (priv->hw_algo) {
  68         case HW_ALGO_TOGGLE:
  69                 /* Toggle output pin */
  70                 priv->state = !priv->state;
  71                 gpio_set_value_cansleep(priv->gpio, priv->state);
  72                 break;
  73         case HW_ALGO_LEVEL:
  74                 /* Pulse */
  75                 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
  76                 udelay(1);
  77                 gpio_set_value_cansleep(priv->gpio, priv->active_low);
  78                 break;
  79         }
  80 }
  81
  82 static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
  83 {
  84         priv->state = priv->active_low;
  85         gpio_direction_output(priv->gpio, priv->state);
  86         priv->last_jiffies = jiffies;
  87         gpio_wdt_hwping((unsigned long)&priv->wdd);
  88 }
  89
  90 static int gpio_wdt_start(struct watchdog_device *wdd)
  91 {
  92         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
  93
  94         gpio_wdt_start_impl(priv);
  95         priv->armed = true;
  96
  97         return 0;
  98 }
  99
 100 static int gpio_wdt_stop(struct watchdog_device *wdd)
 101 {
 102         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 103
 104         priv->armed = false;
 105         if (!priv->always_running) {
 106                 mod_timer(&priv->timer, 0);
 107                 gpio_wdt_disable(priv);
 108         }
 109
 110         return 0;
 111 }
 112
 113 static int gpio_wdt_ping(struct watchdog_device *wdd)
 114 {
 115         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 116
 117         priv->last_jiffies = jiffies;
 118
 119         return 0;
 120 }
 121
 122 static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
 123 {
 124         wdd->timeout = t;
 125
 126         return gpio_wdt_ping(wdd);
 127 }
 128
 129 static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
 130                                void *unused)
 131 {
 132         struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
 133                                                   notifier);
 134
 135         mod_timer(&priv->timer, 0);
 136
 137         switch (code) {
 138         case SYS_HALT:
 139         case SYS_POWER_OFF:
 140                 gpio_wdt_disable(priv);
 141                 break;
 142         default:
 143                 break;
 144         }
 145
 146         return NOTIFY_DONE;
 147 }
 148
 149 static const struct watchdog_info gpio_wdt_ident = {
 150         .options        = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
 151                           WDIOF_SETTIMEOUT,
 152         .identity       = "GPIO Watchdog",
 153 };
 154
 155 static const struct watchdog_ops gpio_wdt_ops = {
 156         .owner          = THIS_MODULE,
 157         .start          = gpio_wdt_start,
 158         .stop           = gpio_wdt_stop,
 159         .ping           = gpio_wdt_ping,
 160         .set_timeout    = gpio_wdt_set_timeout,
 161 };
 162
 163 static int gpio_wdt_probe(struct platform_device *pdev)
 164 {
 165         struct gpio_wdt_priv *priv;
 166         enum of_gpio_flags flags;
 167         unsigned int hw_margin;
 168         unsigned long f = 0;
 169         const char *algo;
 170         int ret;
 171
 172         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 173         if (!priv)
 174                 return -ENOMEM;
 175
 176         priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
 177         if (!gpio_is_valid(priv->gpio))
 178                 return priv->gpio;
 179
 180         priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
 181
 182         ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
 183         if (ret)
 184                 return ret;
 185         if (!strcmp(algo, "toggle")) {
 186                 priv->hw_algo = HW_ALGO_TOGGLE;
 187                 f = GPIOF_IN;
 188         } else if (!strcmp(algo, "level")) {
 189                 priv->hw_algo = HW_ALGO_LEVEL;
 190                 f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
 191         } else {
 192                 return -EINVAL;
 193         }
 194
 195         ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
 196                                     dev_name(&pdev->dev));
 197         if (ret)
 198                 return ret;
 199
 200         ret = of_property_read_u32(pdev->dev.of_node,
 201                                    "hw_margin_ms", &hw_margin);
 202         if (ret)
 203                 return ret;
 204         /* Disallow values lower than 2 and higher than 65535 ms */
 205         if (hw_margin < 2 || hw_margin > 65535)
 206                 return -EINVAL;
 207
 208         /* Use safe value (1/2 of real timeout) */
 209         priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
 210
 211         priv->always_running = of_property_read_bool(pdev->dev.of_node,
 212                                                      "always-running");
 213
 214         watchdog_set_drvdata(&priv->wdd, priv);
 215
 216         priv->wdd.info          = &gpio_wdt_ident;
 217         priv->wdd.ops           = &gpio_wdt_ops;
 218         priv->wdd.min_timeout   = SOFT_TIMEOUT_MIN;
 219         priv->wdd.max_timeout   = SOFT_TIMEOUT_MAX;
 220         priv->wdd.parent        = &pdev->dev;
 221
 222         if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
 223                 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
 224
 225         setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
 226
 227         ret = watchdog_register_device(&priv->wdd);
 228         if (ret)
 229                 return ret;
 230
 231         priv->notifier.notifier_call = gpio_wdt_notify_sys;
 232         ret = register_reboot_notifier(&priv->notifier);
 233         if (ret)
 234                 goto error_unregister;
 235
 236         if (priv->always_running)
 237                 gpio_wdt_start_impl(priv);
 238
 239         return 0;
 240
 241 error_unregister:
 242         watchdog_unregister_device(&priv->wdd);
 243         return ret;
 244 }
 245
 246 static int gpio_wdt_remove(struct platform_device *pdev)
 247 {
 248         struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
 249
 250         del_timer_sync(&priv->timer);
 251         unregister_reboot_notifier(&priv->notifier);
 252         watchdog_unregister_device(&priv->wdd);
 253
 254         return 0;
 255 }
 256
 257 static const struct of_device_id gpio_wdt_dt_ids[] = {
 258         { .compatible = "linux,wdt-gpio", },
 259         { }
 260 };
 261 MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
 262
 263 static struct platform_driver gpio_wdt_driver = {
 264         .driver = {
 265                 .name           = "gpio-wdt",
 266                 .of_match_table = gpio_wdt_dt_ids,
 267         },
 268         .probe  = gpio_wdt_probe,
 269         .remove = gpio_wdt_remove,
 270 };
 271
 272 #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
 273 static int __init gpio_wdt_init(void)
 274 {
 275         return platform_driver_register(&gpio_wdt_driver);
 276 }
 277 arch_initcall(gpio_wdt_init);
 278 #else
 279 module_platform_driver(gpio_wdt_driver);
 280 #endif
 281
 282 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 283 MODULE_DESCRIPTION("GPIO Watchdog");
 284 MODULE_LICENSE("GPL");